Saturday, February 11, 2012

WA Endemic Subspecies - An Annotated List: Part 1: Southwest

This is the first of three checklists of bird species and subspecies endemic (or nearly so) to the state of Western Australia. The distributions of these, for the most part, correspond approximately to the three biogeographic ‘refuge’ areas of the State (the South-west, Hamersley, and Kimberley refuges), which due to their rockier and more hilly terrain offered climatic refuge during cyclical periods of aridity throughout the Pleistocene. These refuges are, in turn, separated from each other (and those of neighbouring States) by coastward extensions of the less hospitable arid interior, namely the Nullarbor, Murchison, Canning, and Bonaparte paleo-barriers.

The South-west region has a very high level of botanical and faunal endemism, and birds are no exception – in fact with now 15 endemic full species (or 16 if you accept Western Fieldwren), South-west WA is rivalled only by far-north Queensland as an endemic bird region within Australia. What is probably less well appreciated is the high number of endemic bird subspecies in the greater South-west region, several of which are potential candidates for splitting as full species once molecular phylogenies are investigated. An even greater number are shared with South Australia’s Eyre Peninsula, due to the former presence of a continuous belt of mallee below the Nullarbor cliffs in times of lower sea levels, which made the Nullarbor Barrier much leakier than it is today. We include some of these ‘almost endemics’ here (ie. range extends a small way into SA), but only for those subspecies which do not - according to Schodde and Mason’s distribution maps [1] - extend fully into the Eyre Peninsula itself.

For Australian listers - Introduced species established only in WALaughing Dove Streptopelia senegalensisMute Swan Cygnus olor

(* = possible future splits)

Notes on SubspeciesExcept where stated, subspecies descriptions follow Schodde & Mason Directory of Australian Birds [1] (=S&M) for passerines, and Handbook of Australian, New Zealand and Antarctic Birds [2] (=HANZAB) for non-passerines. Endemic species are included where these contain multiple subspecies.

Cape Barren Goose (race grisea)
“Recherche Cape Barren Goose”
Smaller, with a more extensive white ‘cap’ and slight brown tint. Breeds on the Recherche Archipeligo but strays to the mainland from Esperance to Cape Arid, mainly in summer. Vulnerable.

The WA race grisea of the Cape Barren Goose, a regular visitor to the golf course at Esperance.

Musk Duck (race lobata)A recently recognised split from eastern menziesi, recognised on the basis of a different display call and 0.36% divergence on mtDNA.Little Shearwater (race tunneyi)One of the ‘littlest’ of the Little Shearwaters, with a similar plumage but a shorter wing and tail than the eastern nominate form. Unlike other local shearwaters, it breeds in winter-spring (May to December) when the Leeuwin Current is strongest along the south coast.

Little Shearwater Puffinus assimilis race tunneyi. This photo, taken on the 2012 Albany pelagics, is apparently one of very few photographs known of this subspecies at sea. If you have been lucky enough to photograph this subspecies, the WA Museum has requested copies.

Australasian Swamphen (race bellus)
“Western Swamphen”
Distinct for the presence of a blue throat and upper breast overlaying the purple underparts; also some blue on the marginal wing coverts forming a shoulder patch; shorter bill shield; slightly larger [3]. Distributed around Moora to Albany, with an apparently isolated population around Esperance. Has some plumage characters of African birds, but nevertheless shown genetically to lie in melanotus in the recent swamphen breakup.

"Western" Purple Swamphen P. p. bellus, one of the most isolated subspecies in the world.

Brush Bronzewing (race occidentalis)Modest differences include a smaller, yellow-buff (not chestnut) cap on the forehead, and a paler back.

Brush Bronzewing P. e. occidentalis at Cheynes Beach

Red-tailed Black-Cockatoo (race naso)
“Forest Red-tailed Black-Cockatoo”
Has a more robust and ‘bulbous’ bill than the northern wheatbelt/arid zone form samueli; female has a red-orange tail rather than orange-yellow, and brighter spots and barring. Declining and now “rare to uncommon” [4], though it has possibly increased in the southern Swan Coastal Plain and Perth Hills in recent years, and is even regular in some southern suburbs of Perth. Note the central inland form samueli is steadily encroaching into the south-west, and is becoming regular in the wheatbelt [3]; this mid-west population of samueli is itself long isolated from the central desert population [2] and may be a subspecies in its own right.

Forest Red-tailed Black-Cockatoo (C. b. naso). While the plumage of the males is indistinguishable from the inland race samueli (but with a more bulbous bill), females are more noticeably brightly patterned.

Western Corella
Nominate form pastinator is now restricted to the Lake Muir and Rocky Gully areas; more widespread derbyi (New Norcia, Wongan Hills, Wubin, Moora areas) is smaller in size, and has a shorter bill and slightly less red in the lores. The name derbyi (which takes precedence over synonym butleri) springs from an unfortunate mix-up when the notoriously over-eager Mathews accidentally lodged the type specimen as a new Little Corella subspecies from Derby!

Regent Parrot (race anthopeplus [westralensis])
Has a slightly darker green body (ie. less yellow) and is more evenly toned than the scarcer eastern form monarchoides. Previously the eastern form took anthopeplus until it was noticed that the engraving of the type specimen in Edward Lear’s The Parrots clearly shows the western form [2].

Australian Ringneck (race semitorquatus)
“Twenty-eight Parrot”
Distinct for its red forehead mark, and its lighter green, not yellow, belly which lacks a sharp cut-off from the breast. Slightly larger than the inland “Port Lincoln Parrot” zonarius, with which it hybridizes in a broad hybrid zone across the northern coastal plain (including Perth) and central-southern Wheatbelt. Also well-known for its classic “twenty-eight” call, which zonarius almost never uses (though north-west occidentalis does). However a molecular study of the ringneck complex [5] found that semitorquatus was paraphyletic, and would not be recognised by any molecular-based species concept even if the group is re-split in the future.

A typical "Twenty-eight Parrot", B. z. semitorquatus, photographed near Bridgetown. Further north around Perth, hybrid birds are commonly seen, typically with the red supranasal spot of semitorquatus, but with more yellow on the belly

Western Rosella
The threatened wheatbelt form xanthogenys is distinct: more blue (ie. less green) on the wing and tail; males have a slightly paler cheek patch, and a red not green back; females have a redder belly. Found in the outer wheatbelt (eg. Southern Cross/Hyden/Bruce Rock to Norseman), typically in association with Rock Sheoak Allocasuaria huegliana [3], but is declining. The two subspecies hybridise in a narrow hybridization zone following the eastern Darling Range and Stirling Ranges.

Western Ground Parrot [aka Ground Parrot (race flaviventris)]
Lighter underparts; fainter barring on the belly; generally lighter green all over [3]. This is now an undisputed split following conclusive molecular work published in 2010 [6], though some checklists (looking at you BirdLife) refuse to recognise this. Endangered.

Splendid Fairy-wren (race splendens)
“Banded Fairy-wren”
The western nominate splendens is distributed throughout the southwest and most of the mid-west and inland Gascoyne, only hybridising with centralian callainus beyond a line Wiluna to Laverton. The male is more uniformly deep blue (ie. back is same deep blue as breast, not turquoise); has a narrower black band on the nape; and no black bar across the lower back.

Southern Emu-wren (race westernensis)
Distinct from eastern forms for its white (not buff) streaking on the ear coverts, and bluer supercilium; coarser black streaking; also larger size [7].New Holland Honeyeater (race longirostris)The south-west population is isolated, and has a smaller and narrower moustachial (malar) stripe, and a bill about 10% longer than the common south-east form. Recent genetic work by Dolman & Joseph [16] found a surprising 1.23% ND2 divergence from eastern birds, which could be taken to indicate a split is warranted.

Western race of of the common and widespread New Holland Honeyeater.

White-cheeked Honeyeater (race gouldii)Like the New Holland Honeyeater, this is widely isolated from the east coast nominate, and distinct: much smaller pear-shaped (vs. fan-shaped) cheek patch; longer more robust bill; broader shaft streaks on the breast and belly; males slightly larger in several measurements [2]; and a “louder and more intense” call [3]. Quite possibly a future split, in light of the status of its relative New Holland Honeyeater; C&B [9] note gouldii is “…treated as a separate species by Gadow 1884…their species status warrants investigation”.

The western subspecies of White-cheeked Honeyeater, P. n. gouldii, could turn out to be a full species - perhaps the 'Moustached Honeyeater' of old?

Yellow-throated Miner (race obscura)“Dusky Miner”The south-west form is distinctive compared to the arid form wayensis: darker on the dorsum; darker grey on the throat and breast; heavier mask; lack of yellow on the throat (hence the common name is inappropriate); and a grey not white rump (so even the alternative species name of “White-rumped Miner” is ill-fitting). Thus it is more similar to the Black-eared Miner Manorina melanotis, a fact tied into some of the controversy around the recognition of that species (argued as a subspecies by S&M). It intergrades with wayensis across a line roughly Moora to Esperance.

A 'Dusky Miner' photographed on the outskirts of Perth, showing the overall darker colour reminiscent of the rare eastern Black-eared Miner.

Singing Honeyeater (race virescens)This south-west (and adjacent western SA) nominate is larger, browner above (ie. less olive), more heavily streaked on the underparts, and has less yellow wash on the throat and breast. It intergrades with the smaller, paler inland form forresti abruptly through the outer wheatbelt. Rottnest Island birds are famously larger - 21% heavier [11] - and darker than adjacent mainland birds. However, despite once being recognised as a separate species ‘Rottnest Island Honeyeater’ by Milligan, S&M dismissed this size difference as “…only slightly [larger]…” and not sufficient for even subspecies recognition.

A Rottnest Singing Honeyeater, showing slightly darker overall colour and more extensive dark streaking on the underparts. The call is also slightly different, and may warrant genetic studies.

Shy Heathwren (race whitlocki)
Indistinct; separated on numerous minor plumage details (eg. whiter tips to wing coverts) and measurements. Western Fieldwren [Rufous Fieldwren (race montanellus)]Recognised as a separate species by S&M and the IOC [8], but not the 'official' C&B [9] list or the WA Museum [10]. Distinctly less rufous over the crown, back and especially the rump; paler eye. C&B stated that “…given the provisional nature of Schodde & Mason’s treatment, [these] are kept as a single species pending further studies” [9], but preliminary genetic work yet to be published apparently suggests Western Fieldwren is conspecific with other WA fieldwren, and the split should be placed be east of the Nullarbor. See this full blog post on the status and distribution of Western Fieldwren.

White-browed Scrubwren (race maculatus)
Has a streaked or ‘spotted’ breast like all WA/SA subspecies (the ‘maculatus group’, historically regarded as the separate species “Spotted Scrubwren” by some), and more yellowish colouration on the flanks and belly. The pigmentation of the underparts clines darkest in the far south-west, possibly fitting with it being an adaptation to feather preservation in high humidity (Gloger’s Rule) [2].

Western Gerygone (race fusca)
A large, dark form with more extensive white tail-tips. Perth is the easiest capital city to see this species.

Yellow-rumped Thornbill (race chrysorrhoa)
Distinct for having a smaller and paler yellow rump, and lack of yellow colouration elsewhere on the body, ie. browner dorsum and more buff underparts. Clines even paler northwards.

White-browed Babbler (race ashbyi)
The largest and palest form, with a fawn colouration across the back. It intergrades with the arid zone form superciliosus through the outer Wheatbelt but it is not clear whether the gradient is steep or gradual. Johnstone & Storr [4] does not recognise the subspecies. Not common in the deep south-west but isolated populations do occur in some areas of karri forest, eg. Denmark-Pemberton area.

Western Whipbird (races nigrogularis and oberon)
The south coastal form is sometimes treated as a separate species, notably by S&M. It has historically contracted in range (listed as vulnerable) and is now restricted to a small area between Two Peoples Bay and Cheyne’s Beach. Less than 50kms away, across a line from the Stirling Ranges to beyond Waychinicup, the western form of “Mallee Whipbird” P. n. oberon occurs apparently without intergradation. Compared to oberon, nigrogularis is deeper olive on the dorsum, has an olive-grey (not pure pale grey) breast, is smaller, and has a shorter tail; oberon is itself distinct from eastern forms in having a black upper edge to the white malar stripe (a feature shared with nigrogularis - this being one of the reasons C&B baulked at the split), and a less distinct subterminal band on the tail. C&B [9] stated that S&M “did not make a compelling case”, and kept the clade as a single species “pending further evidence”. It appears that an unpublished molecular study by Christidis & Norman (in a report for CALM) has subsequently argued against the split of nigrogularis at species level [12]. Early reports of ongoing genetic work suggest that, as in fieldwren, the split with Mallee Whipbird should be placed at the Eyrean barrier.

Copperback Quail-Thrush (race fordianum)
A south-western subspecies split by S&M from arid zone clarum, within a species recently split after discovery of deep genetic divergence across the Eyrean Barrier [16]. The chestnut band across the back is narrower and does not extend onto the scapulars, while the female has only a chestnut wash instead of a band, and russet (not brown) flanks. There is a large zone of intergradation around Kalgoorlie.

Black-faced Woodswallow (race cinereus)
Rather larger; distinctly browner over breast and a ‘sooty cast’ to the back; uniformly black vent.

Australian Magpie (race dorsalis)
“Western Magpie”
These used to be perceived as intermediate between the “Black-backed” and “White-backed” forms of Magpie, particularly because of the distinct white feather edges (creating a coarse scalloped pattern) on the back of females. Intergrades with longirostris through the Murchison and along the mulga-eucalypt line.

Crested Shrike-tit (race leucogaster) “Western Shrike-tit”S&M re-split all the Shrike-tits based on multiple differences, including the tail proportions, wing shape, size, and plumage. Most notably, Western Shrike-tits have a white band between the breast and belly, compared to the wholly yellow belly of Eastern birds. Its call is also quite different from the Eastern Shrike-tit. Despite noting that S&M had uncovered “…difference more than previously appreciated…”, C&B “tentatively” kept the group as a single species pending “…appropriate molecular studies” [9].Grey Fantail (race preissi)
Smaller; throat band very narrow and greyish; reduced white on the longish tail. There is evidence of intergradation with albicauda (the desert “White-tailed Fantail”) along the mulga-eucalypt line. Partially migratory; tends to leave its colder southern breeding areas and expands north as far as the Hamersley Ranges in autumn-winter (whereas albicauda remains sedentary).

Australian Raven (race perplexus)
“Western Raven”
Regarded as quite distinct from eastern birds and almost intermediate between coronoides and Little Raven: noticably smaller; finer bill; shorter throat hackles; more clipped and guttural call. There is some uncertainty whether this is an isolated WA form (split at the head of the Bight), or whether SA’s Eyre Peninsula birds are intergradient between perplexus and coronoides. Authors of a recent worldwide corvid genetic study [15] support the split of coronoides and perplexus as species-level clades, though do not provide detail of genetic distance.

The western race of the Australian Raven has shorter hackles, a finer bill, and different call to the east coast birds, and may explain some reports of Little Crows in Perth from visiting birders familiar with the east coast Australian Ravens.

Scarlet Robin (race campbelli)
Widely isolated from the eastern form, and now under investigation as a likely split after discovery of deep genetic divergence (2.79% ND2) by Dolman & Joseph [16], but the status of birds in SA need clarification first. The male is similar apart from a smaller forehead ‘cap’, but the female is grey (not brown), has a bright white sash on the median coverts, a blacker throat, and a more extensive red scarlet wash to the breast.

Western Yellow Robin (race griseogularis)
The extreme south-west nominate griseogularis has a bright yellow rump, compared to the citrine rump of rosinae, which extends into South Australia. The nominate also has a lighter grey breast band than rosinae. The hybrid zone between the two subspecies approximates a line between Lancelin and Denmark, though Ford (1963) [13] found that birds with bright yellow rumps (thus ‘classic’ griseogularis) were restricted to the Darling Range in the vicinity of Perth, rather than the deep south-west. The northern west coast population of rosinae, found from the coastal northern outskirts of Perth to as far north as Kalbarri, were noted as distinctly smaller by Ford [13] and may also be a distinct race. Both subspecies have been lumped with Eastern Yellow Robin in the past and this is “…yet to receive rigorous investigation” according to C&B [9], though a recent molecular study appears to have put this question to rest, while confirming subspecies status for the two Western forms [14].

Welcome Swallow (race carteri)S&M recognised an eastern and a western form of Welcome Swallow, the latter with a slightly shorter tail (especially in males); slightly smaller; and a slightly longer bill. The range of carteri extends into the Pilbara in winter.Australian Reed Warbler (race gouldi)
Slightly larger and overall darker than the eastern form. Extends into the Kimberley where non-breeding migrants of both subspecies, as well as a poorly-known pale form are thought to occur.

Australian Reed-warbler, race gouldi.

Little Grassbird (race thomasi)
Widely isolated from the eastern form; overall darker, with more distinct striations on the foreneck.

Silvereye (race chloronotus [syn. gouldi])
“Western Silvereye”
Western birds are quite distinct in having the whole of upperparts olive-green, whereas all other Australian forms have a grey back; yellow-green undertail coverts; “…lacks the prenuptial moult which characterises the eastern populations”, according to Serventy & Whittell [7]; also a more rounded wing-tip, reflecting its more sedentary nature compared to the migratory eastern subspecies [2]. Formerly regarded as a separate species, but aligns with the South Australian form on mtDNA and intergrades with it across western SA. There is a simmering argument about the correct subspecific name, S&M and HANZAB arguing for reinstatement of Gould’s chloronotus over gouldi.

The green-backed western race chloronotus of Silvereye.

Australasian Pipit (race bilbali)
Slightly darker form with heavier breast streaking, which often extends onto the flanks or upper belly. Intergrades across the transitional woodland line with the nominate form, (which occupies most of mainland Australia), though range extends a small way into South Australia.

2 comments:

This is brilliant, thank you so much! As I'm heading to Perth from Adelaide on Sunday for four days, there will be some birds that I have never seen before. At least, I am hoping to see and photograph them :) These details really help.